There are many reasons why a person might need a skin graft, anything from burns to birth defects.

Burns
The most common indication for skin grafting is burns, and as such, special attention will be paid here to them. Burns can be from heat, cold, chemicals, or radiation, and generally occur in avoidable circumstances or by accident. Around 70% or burns occur in and around the home, with the others occurring in industry. It is therefore not hard to imagine that most burns occur in children. Indeed accidental death is the leading cause of death for the 0-15 age group. Within that statistic, burns are the second most common accident, with inhalation of a foreign body causing airway obstruction being the most common.

Demographics of burns
The Metropolitan Life Insurance Company reported that in 1911 the mortality rate from burns was 9.1 deaths per 100,000 population. This improved to 2.5 per 100,000 in 1936 and 1.3 per 100,000 in 1950. Today the mortality rate is little better, at 1.27 in 2004.
Burn demographics have been extensively studied and there are many trends that upon inspection are really quite obvious. Infants most commonly have scalds from hot liquids and surfaces. Hot liquids account for 2/3 of fatal male burns and ½ of fatal female burns in infants. Also common are steam burns incurred when a child is placed over boiling water to alleviate respiratory infection symptoms. This is called a “croup-kettle” and is thankfully becoming much less common.
Toddlers, from 1-3 years are most commonly burned by stoves and grates. Many will walk up to a stove and pull down a pot, showering their faces, heads, and arms in scalding liquid. Indeed such stove related injuries account for ½ the deaths in girls and ¼ of the deaths in boys of this age group. In school children, the most common mechanism of injury stems from playing with matches and/or flammable liquids, causing ¼ of deaths. Teenagers and adults as well are most commonly burned by flammable liquids. Burns are commonly incurred by combustion of gasoline or kerosene or butane during filling or when being used to start or feed a fire. Men show a much higher propensity for burning themselves with flammable liquids, while women are much more commonly injured by the combustion of flammable laundry chemicals, and stove related burns kill 2/5 of adult female burn victims. Careless smoking also commonly leads to flaming clothing and extensive burns, causing 1/6 of deaths in this age group.
Burns are ugly injuries that are difficult to treat and repair, and they are therefore quite expensive. It costs an average of $9,000 to treat a serious burn without surgery, and $30,000 on average with surgery. The US spends at least 5.5 billion dollars a year on burn treatments.
Why Skin Grafting?
Burns cause the physical destruction of body tissue. The skin is destroyed, and often underlying tissue is damaged as well. The body is dangerously exposed to the outside environment and the injury is prone to infection. Many of the bodies vessels are hopeless destroyed, and huge amounts of blood, lymph, liquefied fat, and interstitial fluid are lost as they simply flow out of the body. Patients must be given fluids to replace what they are losing, however, without skin it is like pouring water in a sieve. In order to prevent this, and in order to allow the body to begin to heal, the patient must be given a skin transplant. The healthy skin will block fluid loss and allow the body to struggle towards homeostatic levels of fluids and electrolytes. This aspect of skin grafting is so important for burn victims that often skin substitutes or even porcine skin tissue will be used to close the wound, even though the body will eventually reject them. These treatments are only directed at sealing the wound and giving the body a chance to right itself.
Besides preventing fluids from getting out, the skin also provides a necessary physical barrier to keep bacteria from getting in. Burns are hog-heaven for bacteria – filled with dead tissue and blood clots to feast on. Burn patients will always get antibiotics, but the best way to keep the bacteria out is with a barrier of skin. All kinds of bacteria love to infest burn wounds, most notably Staphylococcus aureus, Pseudomonas aeruginosa, cloacae, pneumoniae, enterococcus faecalis, acinetobacter baumannii, aspergillus, and candida albicans, with Staph being by far the most common.
Thirdly, as already discussed, extensive skin wounds can become contracted as they heal, and nowhere is this more obvious that in burn victims who do not receive immediate care. Skin grafts replace skin that would otherwise be replaced by contractive scar tissue, and therefore can prevent or repair deforming contractions. Immediate Treatment for burns
Burns are extremely painful, and burn victims should be given pain medication as soon as possible. Generally they will receive about a gram of morphine to deal with the destroyed nerves that will continue to communicate pain signals despite their condition. In addition, as mentioned earlier, one of the biggest problems with burns is the massive fluid loss. As a consequence one of the first symptoms of a burn is decreased blood volume leading to hypoperfusion or shock. Therefore the most important immediate treatment, is for shock. Fluids should be administered, the legs elevated, and the patient kept warm.
To prevent fluid leekage and to prevent fluid build up, or edema, the patient should be wrapped in pressure dressings over the wound. Sterile gauze should be wrapped tightly in many layers directly over the wound, preventing fluid loss and blocking infection. It has been shown that edematous tissue, filled with body fluids, is a very nutritive media for bacteria, so preventing edema helps prevent infection.
Experiments have been made with substances to reduce blood and other fluid loss. In World War I the Germans gave burned soldiers gum acacia, a large polysaccharide too large to leave the circulation. The theory was that it would increase osmotic colloidal pressure and oppose fluid loss from vessels. Later similar experiments were conducted with Polyvinyl pyrrolidone or PVP, and dextran another large polysaccaride. All of these succeeded in slowing plasma leekage and fluid loss, but only for an hour or two. Eventually these patients will need blood.
Whole blood transfusion is the hands-down best treatment for burn shock. Evan’s formula, generally accepted, proscribes 1 cc of blood and 1 cc of electrolyte fluid for every 1 kg of body weight times the percentage of body surface area burned. This can add up to several liters of blood for a large patient or one with severe burns. This volume is administered over 24 hours, and generally half of the same volume will be administered during the second 24 hours.

Grafting
After the patient has been stabilized the most important consideration is sterility. As soon as possible the slough, the dead tissue, will be surgically removed. All dried serum, blood clots and necrotic tissue of all descriptions must be removed, and the wound must be washed regularly to prevent infection. All dead tissue will generally be removed after three or four days. During this time fluid maintenance remains important, and patients are also encourage to eat and drink as much as they can to feed their body, as healing from a burn is a very physically demanding process. The underlying tissue will begin froming granulations, small buds of proliferating tissue, after about a week, indicating the body is starting to heal and grow again. At this time, the wound is ready to receive a skin graft. The sooner the graft is applied the better in all cases, however, if there is an infection it is important to resolve it before putting on a graft, even though this means delaying grafting.

Necrotizing Fasciitis
Much more commonly known as flesh-eating bacteria, necrotizing fasciitis is the bacterial infection of the underlying connective tissue, or fascia. It can be caused by streptococcous A, vibrio vulnificus, clostridium perfringens, and bacteroides fragilis, with strep A being the most common by far. These bacteria will often penetrate a deep wound, and can occur due to animal bites or swimming in unclean water. The symptoms will begin with itchiness that will procede to discoloration, swelling and pain as the underlying tissue dies. Eventually the skin will blister out and ooze significant blood and pus. The infection spreads very rapidly, so the best treatment is rapidly excising all infected tissue and a healthy margin of uninfected tissue as well, and covering the area with a skin graft.

Syndactylism
Syndactylism is a condition where two or more fingers are cojoined. This is a not-terribly uncommon birth defect. In utero all of our hands begin with webbing between the fingers. For most of us that webbing disappears and skin forms all the way around the fingers. However, if this does not happen, it is easily corrected after birth. The fingers will be separated and small skin grafts will be put on the insides of the fingers. If more than two fingers are conjoined it is best to do the operations in a stepwise manner. If done all at once the middle finger would require skin grafts around pretty much all of it’s circumerferance, and this is always a bad idea and is less successful.

Non-healing Ulcers
The second largest patient population receives skin grafts to heal ulcers, which come in two principle forms, diabetic and decubitius ulcers. An ulcer is caused by the death of tissue due to oxygen starvation. Severe hypoperfusion of some area of tissue results in anoxia and cell death. This results in the depositing of thick, dense scar tissue, and generally these ulcers will continue to grow as more and more tissue dies.
Diabetic Ulcers
Diabetics are predisposed to atherosclerosis. The reason for this is still obscure, but it is perhaps because of elevated LDL and VLDL levels, elevated plama fibrinogen levels, or increased platelet adhesiveness. In addition, diabetics seem to have a much higher incidence of atherclerosis in leg vessels, especially the tibial, peroneal, and popliteal ateries and their capillary beds. Combined with frequent pitting edema in the lower legs, many older diabetics may not even have a palpable distal pulse in their lower extremities. This leads to decreased blood flow to some portion of leg tissue, and if sever enough this tissue may become anoxic and ulcerous.
Diabetics are also prone to peripheral neuropathies caused by vascular disease, myelination problems, and decreases in sodium/potassium pump activity. One common symptom of this is decreased sensation or loss of sensation in the feet. This can lead to unnoticed injury, or more often sores that develop from shoes that become too tight. As feet swell from edema, shoes may become increasingly tight without a patient noticing, and this could cause an ulcerous sore to develop.
There are 16 million diabetics in the US, and ulcerous lesions account for more diabetic hospitalizations than any other secondary issue. About 15% of diabetics will get a diabetic ulcer, and about 12-20% of these patients will require amputation. Indeed diabetic ulcer related amputations account for half of non-traumatic amputations every year, about 50,000 amputations at a cost of about $500 million annually. Decubitus Ulcers
Decubitus comes from the latin “decumbere” which means to lie down. These ulcers are also commonly called bed sores or pressure sores, and are found in sedentary and prone patients. These ulcers are again necrotizing tissue that died from oxygen starvation. In this case, simple pressure forced blood out of the tissues. The body is capable of handling lots of pressure quite well transiently, but extended pressure can be dangerous. Capillary pressure is only about 30mm Hg, so not much pressure is required to force blood out of a tissue. Indeed a patients own weight is generally enough.. The pressure, generated by the patients own bony prominences, also forces the lymphatics closed, which leads to the build up of anaerobic metabolic products, which are toxic and increase the rate of tissue necrosis.
These sores are prone to infection, especially given their location. If tissue is kept moist by sweat, urine, or fecal matter it will become overly soft and hydrated. This skin will be more easily macerated and torn, injuries that could easily develop into ulcers, and this hydrated tissue is also more prone to infection.
These sores develop, predictably, on coma patients, the disabled, the elderly, and paraplegics most commonly, and their incidence increases with obesity. 96% of decubitus ulcers occur on the lower body, with 67% on the hips and buttocks and 29% on the lower limbs. 65% of patients with decubitus ulcers are over the age of 70, and there is a 15-25% incidence among nursing home patients. Pressure sores are expensive, adding an average of $15,000 of costs a year, and a full removal with graft costs about $120,000. Needless to say this is a lucrative industry, and indeed ulcer related surgeries pay from 3-5 billion dollars in the US annually as of 2004.

Marjolin’s Ulcer
Marjolin’s Ulcer is also more correctly called Marjonlin’s carcinoma. It is a squamous carcinoma that arises in burn scars that are under tension. It will appear as a raised plaque of pink tissue that may blister and bleed openly. These kind of ulcers are common on the backs of knees and elbows or on the fronts of upper thighs. Burn scar tissue cracks and tears, and these wounds struggle to heal due to limited vascularization. These patients should have had skin grafts in the first place, and will likely require one over the ulcer after it is removed.

Granuloma Inguinale
This disease is caused by a sexually transmitted bacteria, Calymmatobacterium granulomatis. This little bugger gets spread mostly in Southeast India, Guyana, and New Guinea, but several cases are treated each year in the US. This bacteria causes genital tissue to form granulation tissue which eats genital skin away to a raw, red, granulated surface. This granulated skin is highly irritable and bleeds easily. The infection is relatively easily corrected with antibiotics, but the destruction of gential tissue is often only reparable with a full skin graft.

Congenital Absence of a Vagina
Also called Vaginal Atresia, this is a congenital birth defect that results form the failure of the Mullerian ducts to fully migrate. This causes vaginal agenesis, the vagina is never formed. In most patients the uterus and ovaries develop normally, as does external genitalia. The problem is often not detected until puberty. Pubertal development will be normal, but there will be no menses. Instead there may be cyclic abdominal pain. Because the uterus is intact, it is possible to cut these women a vagina. A vaginal vault will be surgically created and will be line with a split-thickness skin graft from the upper inner thigh. The graft will be held in place by a mold inserted into the vagina, which must remain for several days, and which must be inserted daily for several months to prevent the grafts from fusing. As a result, the operation is not considered until a girl is old enough to perform this daily dilation herself. The graft is generally very successful, however the tissue will enver become vaginal muscosal epithelium. There will be no mucosal secretion, or change in morphology. It will simply be thigh skin in an unusual place. Intercourse is possible, as is natural conception, but babies are generally delivered by c-section to avoid complications with the graft.

Pruritus Vulvae and Pruritus Ani
Pruritus comes from the latin and means to itch. These two conditions are exactly what they indicate, severe itchiness of the vulva and anus. This is caused by excessive histamine levels in the effected areas, and can cause severe and debilitating swelling and irritation, and eventually may lead to tissue death, blistering or bleeding. In many cases the area may be scratched raw. If the skin damage is extensive enough the old skin may need to be removed and replaced by a skin graft. Sometimes the problem is secondary. One treatment for pruritus is x-radiation, however if this treatment is not carefully controlled it can easily make the problem worse, as the sensitive tissue is susceptible to x-radiation burns that will cause further swelling and blistering. Anal and vulval grafts must be accompanied by treatment to achieve constipation for at least a week after the injury because anal dilation could tear a graft that hasn’t fully healed. This makes this one of the most unpleasant of skin grafts, and requires extended liquefied diet.

Ear Reconstruction
Ears are commonly damaged in trauma or by burns, and they are also one of the more susceptible body parts to damage due to freezing. It is also possible to be born with a congenital lack of ears. In all of these cases it is possible to rebuild the ear, or even to create one from scratch. Ears can be restructured with a small graft of tissue from the buttocks quite easily. If the whole ear is missing, a thick graft will be placed over the area, and allowed to heal. Later an incision will be made that will separate the ear from the head, and then the folds of the pinna are free to be surgically constructed out of the available tissue.

Nose Reconstruction
The nose, like the ears, is often the victim of disfiguring trauma. Generally a nose can be relatively easily reconstructed with tissue from another part of the body. Cartilige from the upper ear, flesh from the upper thigh or buttocks, or a pedicle flap from the forehead (the ancient Indian method) are all used, depending on the individual patient and the amount of tissue needed.
Some luetic and pyogenic bacteria infect and destroy the mucosal lining of the nose, which can lead to chronic nose-bleeding and upper respiratory infection. Congenital vestibular atresia is similarly a congenital lack of inner nose mucosal epithelium. In these cases very thin skin grafts will be placed inside the nasal canal.

Scalp Replacement
There are several times when all or part of the scalp will need to be replaced. Babies are very occasionally born without a scalp, sometimes even without a skull in some areas. These babies will require immediate skin grafting to cover the area. People with long hair will sometimes get their hair caught in some sort of rotary device, a fan or industrial machine. This entaglement leads very rapidly to severe damage to the scalp, and treatment often involves skin grafting. Sometimes people will receive radiation treatment for ringworm of the scalp, which can lead to radiation burns which can become ulcerous or infected and may require grafting. Luckily, hair follicles are very deep on the scalp, so even if a hairless skin graft is placed over a deep tissue injury, hair will likely grow up through it.

Nevi
Nevi are patches of overgrown melanocytes, the pigment producing cells of the skin. There are many different kinds of nevi, and they can be smooth, bumpy, or hairy, and may be blue, brown, black, red, or yellow. They can occur all over the body at birth, and most will go away spontaneously. The Mongolian spot, for example, a bluish stain about an inch in diameter is observed somewhere on 95% of black infants, and disappears generally by age 4. Some Nevi, singular nevus, do not go away, in which case a patient may want them removed for cosmetic reasons especially if they are on the face. Most common is the nevus flammeus, a reddish-pink patch of skin often seen on the face. These nevi can be easily removed surgically, and will often heal naturally if they are not very deep. However, many larger or deeper nevi will require a skin graft following removal, usually taken from the neck or groin.

Hemangiomas and Lymphangiomas
Hemangiomas are bright red formations on the skin. They result from the abnormal transformation of epithelial cells into tubular capillary-like formations. This forms blood-vessel rich masses of tissue. Sometimes these are smooth, so-called Port Wine stains which may not change over the course of a lifetime, and require no treatment, unless cosmetic treatment is desired. Cosmetic treatment may involve bleaching, or more aggressively, removing the stained tissue and, if needed, replacing it with a graft.
Hemangiomas may be presnt at birth, or they may develop from a less malignant earlier formation. Hermangiomas may grow rapidly, forming a bright red building mass under the skin filled with blood. Sometimes they starve surrounding tissue of blood and ulcerate, or they may become blistered and secrete pus and blood. Removing a hemangioma must be done carefully, since it is basiclly just a bag of blood, and a rapid skin graft is very important to facilitate the healing process.
Lymphangiomas are very similar but instead of being filled with blood vessels, these growths result from a build up of lymph and pus.

Elephantiasis
This is not the disease publicized by the famous “Elephant Man” movie, which was actually Proteus Syndrome. Elephantiasis is also deforming, and occurs from the thickening of skin and underlying tissues. It is generally associated with a cessation of lymphatic function, most often as a result of a parasitic disease called lymphatic filiariasis. The lymphatic obstruction is thought to cause continuous mild infections and edema, as well as tissue thickening, resulting in the characteristic bulging appearance of the legs and genitals of patients. To reduce this deformity, patients will have the thickened tissue removed and replaced by a skin graft. This is extremely effective. Usually, the deformity will begin to reform. There has been no cure for the disease itself, but skin grafting can be an effective and dramatic solution to the worst symptoms.

Tattoos
A tattoo that costs $50 and half an hour to put on can cost as much as $7000 to remove over the course of a year. Tattoo ink is injected all the way down into dermal tissue, so tattoos are almost full thickness formations. There are numerous techniques employed for tattoo removal. Simple dermabrasion may be employed, numbing or freezing the skin and then simply sanding it down. Laser surgery and various acidic peels are also options, and smaller tattoos can be simply cut out and sewn up, but for larger, deeper, and darker tattoos, the hardest ones to fade or sand out, the best option may be a skin graft. The tattooed skin will be fully excised and skin will be grafted from the upper thigh, lower back or buttocks. Such a surgical approach is certainly the most invasive approach to tattoo removal, but it may also be considered the most thorough. The disadvantage is that skin must be removed from some other body part, creating a whole new wound and scar, and in addition, the graft will never restore the skins original color and smoothness, despite the ever increasing quality of skin grafts.

Compartment Syndrome
Compartment syndrome, like decubitus and diabetic ulcers, is caused by tissue death due to anoxia. In compartment syndrome, some abnormal activity causes an increase in pressure under the fascia. The fascia is a very tough and inflexible connective tissue membrane, and if there is a build up of blood or lymph, or inflammation due to infection followed by leukocyte infiltration, there will be an increase in compartment pressure, as the fascia is unable to stretch to accommodate the increased fluid volume. This increased pressure will compress the muscle tissue inside the compartment, compromising blood flow to the tissue causing anoxia and eventual cell death.
Compartment syndrome can come on fast and is extremely painful. The pressurized compartment will need to be punctured and drained, and dead tissue will need to be excised. Depending on the severity of the tissue damage, this fasciotomy may leave a very large wound that will need to be covered in a skin graft.

Radiation Burns
Radiation burns can be caused by any type of radiation; UV rays, X-rays, cathode rays, or atomic rays. UV damage is really just sunburn, and even an extremely serious sun burn will not require as drastic a treatment as a skin graft. Scaring resulting from a third-degree sunburn may be treated cosmetically by skin-grafting, especially if the scarring is facial.
Atomic radiation damage is also rarely an indication for skin grafting, mostly because it is incredibly rare. Greusome scenes of dermal injuries from Hiroshima may come to mind, but for the most part all of those burns were predominantly thermal. Atomic radiation will indeed destroy skin with prolonged exposure, but most exposures are accidental and brief, causing blistering and superficial tissue necrosis. Cathode ray burns are the very same, with very few cases of accidental exposures causing superficial skin burns.
X-rays are a different story, mostly because they are so widely applied in modern medicine. X-rays are obviously used on thousands of patients every day with no adverse effect, and indeed modest exposure to x-rays is not a serious problem, but they put you in a lead vest for a reason. Longer exposure to x-rays causes thickening of arteriole walls, making them less permeable to oxygen. This leads to subcutaneous ischemia and can progress to localized tissue necrosis. This presents as characteristic “coal spots,” dark subcutaneous spots of necrotizing tissue. These coal spots will grow as dead tissue is replaced by fibrous tissue, creating further barrier to tissue oxygenation. Tissue death will continue and the spots may eventually develop into surface ulcers. If the tissue necroses is significant or deep enough the lesion may require skin grafting after excision.
In physicians these burns are seen mostly on the hands. In dentists this is due to holding x-ray films in patients mouths during x-rays. Other physicians will reduce difficult fractures under an active fluoroscope. In the general population, x-ray burns can be all over. X-ray treatment is used to treat acne, eczema, plantar warts, port-wine stains, epidermophytosis, and pruritis. It has even been used as a commercial epilator to remove unwanted body hair. In all of these cases where there is a cosmetic aspect and the patient is very eager for a successful treatment, the radiation may be over-applied and may cause burns over the treated area.

Eye-Brow Replacement
The eye-brow is one of those features that we generally take for granted until we idiotically shave or singe it off and realize that we all look much more like aliens without our eyebrows. Injury can often result in destruction of eye-brow tissue, but we need not worry because eye-brows are more easily replaced than you would think. Transplanted skin retains its morphology, so a small hairy skin graft is taken from above the ear or at the nape of the neck and is transplanted above the orbit. The hair will continue to grow long is not kept trimmed. Alternatively, a patient can choose to transplant half of an existing eye-brow to the other side. This is drastically more popular in women, who want narrower eye-brows anyway.

Eye-Loss
Patients that lose an eye often opt to have a prosthetic put in. Before this can occur, the patient will generally receive a very thin skin graft on the inside of the eye-socket. This ensures that the prosthetic eye will be in contact with tough skin, and not sensitive retinal tissue. It will also keep the socket dry and free from pus or swelling. If no prosthetic is desired, a skin graft will generally be placed over the empty socket and allowed to heal over.

Power Take Off Injuries
This class of injuries is caused by pants legs getting caught in rotating machinery like a corn picker, tractor wheel, or thresher. The pant leg will generally tear and be rapidly and tightly wrapped around the leg. This will often shear off skin all around the leg as the fabric tightens and winds, and damage is very often done to the scrotum and groin. Other sources of scrotal injuries exist, but none are as common. Leg damage may require skin grafting. Scrotal damage, however, cannot be repaired with a skin graft due to the highly specific morphology of scrotal skin. In this case, the testes will generally be placed in surgically created pouches in the upper thighs. Patients with this arrangement have been fertile for as long as eight years afterward.